To determine the concentration of minerals of interest, the methods commonly used in the prior art consider the analysis of debris samples generated in the drilling of pits performed on a field whose feasibility of exploitation is to be determined. Analysis of debris or dust produced in drilling is performed, upon selection of samples, either on the drilling site or laboratory. The methods known in prior art for analysis of valuable materials concentration use different properties of the materials of interest to determine its presence and to what extent they are present.
Debris generated in a pit under excavation generally is extracted manually or mechanically, often intrusively, and taken to laboratories where is analyzed to determine its grade using chemical tests or similar.
International Patent Application WO95/09.962 is known from the prior art and discloses a system for capturing samples of the material excavated from a pit. A container that can be lowered into the pit on a cable and captures samples once inside is disclosed. After the capture, the samples can be raised to be analyzed. As usual in the prior art, the samples should be handled and transported to a laboratory for analysis and determine the degree of mineral concentration. The disadvantages of this method are: requires the drilling of the entire pit or at least part thereof, after which drilling must be stopped to remove the samples; while removing and handling samples, they become contaminated during the rise of the element that captures, generating measurement error; and cause samples must be sent to a laboratory, the response is slow, in the order of several hours, which means that when the results are available, the drilling machine is already operating elsewhere, generating two types of errors; type one error, continue drilling wherein the material is sterile, or type two error, stop drilling a place which contains valuable or commercially important minerals.
International patent WO2010/052.645 is also known from the prior art and discloses a method and a system of collection and analysis for in situ determination of concentrations of minerals in granular material originating from a shaft under excavation, in a continuous, non-intrusive manner in real-time. According to the present invention granular material collected passes to a granular material collector, subsequently entering a reading module which determines the concentration of different materials by atomic absorption spectroscopic methods operating at certain wavelengths in the visible and infrared spectrum. The collection of granular material comes from drilling dust goes up a bit of a hole digging. The concentration data of different minerals in the granular material being analysed at a given moment may be processed and transmitted to establish and/or correct logistic and operational procedures. The disadvantages of the technology disclosed in this patent application are: working with fine particulate material with humidity less than 6%, thus requiring a drying system; besides, in order to quantify the absorption of electromagnetic radiation, this technology requires a reference material. The patent application WO2010/052.645 further requires that incident radiation passes through the sample at specific wavelengths of visible and infrared spectrum between 0.2 and 22 μm to determine the mineral grade; this technology is also limited in that is not possible passing through samples of more than 2 mm in thickness, that is, can only read a thin film of material. Moreover, the range of molecular spectroscopy of patent application WO2010/052.645, whose incident radiation operates in the range of 0.2 to 22 μm, does not allow to excite all molecules and mineral compounds, among them many that also contain copper, which generates a measurement error, and it is possible to report a zero copper grade when the actual grade is greater than zero, a result of not being able to detect these compounds and molecules. Additionally, the reading means specified in the patent application WO2010/052645 uses photo-detectors, avalanche photo-diodes or photo-transistors, or charge coupled device (CCD sensors), which are very sensitive to temperature and its variations, which also generates measurement error of the grade.
Another prior art document U.S. Pat. No. 3,980,882(A) proposes an apparatus for analyzing flowable substances such as slurries using techniques such as X-ray fluorescence, infra-red reflectance or emisson spectrography. The material to be analyzed is caused to flow over a plate in a very thin film so that a quantitative measurement of the elements of interest in the material can be made by analytical systems. The invention comprises an apparatus for use in the analytical determination of a given substance in a flowing material, said apparatus comprising: a member having an upwardly facing substantially planar surface; means for causing a stream of said material to flow in a substantially invariant manner over said surface in the form of a thin film; and an analytical system comprising means selectively responsive to electromagnetic radiation of at least one wavelength which corresponds to a spectral characteristic of said given substance, said selectively responsive means being disposed in fixed relationship to said surface out of contact with said film for receiving radiation travelling from the vicinity of a given portion of said film. The disadvantages of the technology disclosed in this patent are that the material should flow over a plate in a substantially invariant manner in the form of a thin film, making impossible to analyze well flows containing solid particles, since these introduce variability in the film thickness and tends to scatter spreading by gravity on an inclined plane; the technology does not work well with fine powders, which contain the highest concentrations of valuable minerals and tend to be more volatile, which may damage the analytical system in the presented configuration or escape to their measurement; the need to operate with a thin film prevents passing larger flows against the analytical system, or, if required, would be necessary to cover an area of large extent.
The U.S. patent application US20100278302 (A1) is known from the prior art and discloses a specific element detecting apparatus for detecting the presence or absence of a specific element or the concentration of the specific element in a measurement target, characterized by providing transporting means that transports the measurement target, providing fluorescent X-ray measuring device that radiates an X-ray to the measurement target and measures a fluorescent X-ray generated thereby to detect the presence or the content concentration of the specific element, above midstream of a transporting path of the transporting means, inserting a resin film between a measuring window of the fluorescent X-ray measuring device, through which the fluorescent X-ray is introduced, and the measurement target on the transporting means, and feeding a clear part of the fresh resin film between the measuring window and the measurement target along with repetition of detection of the specific element. The disadvantage of this apparatus is that the unconfined horizontal transport of the target material to be measured by conveyor belts or other similar means does not prevent the loss of finer and volatile particles, which contain higher concentrations of valuable minerals.
In many production processes related to the extraction and processing of materials or substances of interest from certain sets of raw materials is essential to know quickly and accurately the concentration or content of certain compounds present in said raw materials. In the case of mining is necessary to know the concentration of one or more valuable minerals, subject to be extracted and processed from a given ore body, to determine the commercial feasibility of its extraction and to optimize its extraction and post-processing. Therefore for determining the mineral content present in the debris of prospective drilling there is need to reduce existent inefficiencies, errors caused by biased sampling, incapacity to take samples from all drilling pits at all depths in a reasonable time and alteration of samples associated with the loss of valuable fine material or contamination with particles suspended in the environment, which causes measurement error.